This article is just plain wrong, from assumptions to conclusion.

First, it claims wind produces more in the day. This is incorrect. Winds pick up in the evening in the most productive regions onshore in the US. This study from Lawrence Livermore National Labs found summer night wind generation to be 55% higher than day. Since wind dominates solar production in the U.S., it calls into doubt the entirety of article.

Second, it completely ignores costs. Storage takes money. More than generation. It also loses energy on uptake and release, and some require active cooling (the heat being the waste from the flow).

To adequately store, you also need to overbuild since solar and wind are intermittent, and you want a high degree of probability of having energy to store.

To reduce covariance, you need to site the renewable generation in disparate locations, with further away being better. After all, if it's not windy or sunny in one region, it's not going to be too different only a few miles away. So now you are siting 100+ miles away, and need to build the transmission infrastructure, and accept some additional line losses, while still not completely mitigating tail risk as the generation is not dispatchable-on-demand.

Solar is a fantastic technology. So is wind. However, their costs along with storage still need to come down a long way to allow for the overbuilding to replace tail risk of no generation.

There was part of a day last year when the entirety of the UK's renewable fleet was producing at 0.3% of capacity. Through importing from Dutch coal and French nuclear, and draining the hydro resources, the country was barely able to meet demand. Another few hours, and the country's grid would have gone down.